We have a Trane Weathertron Xl1200 heating pump with the thermostat pictured below and are trying to replace it with our new Nest thermostat. Our old system has a variable speed air handler and we want to make sure that we hooked up the wiring correctly. We have electric heat with emergency backup. Is the wiring we have correct or do we need to change anything? We have the latest version of the Nest thermostat.